.. todo::

    Joakim: Move this under porting guidelines instead?

.. _license_headers:

###############
License headers
###############
This document defines the format of the copyright and license headers in OP-TEE
source files. Such headers shall comply with the rules described here, which are
compatible with the rules adopted by the Linux kernel community.

New source files
****************

    - **Rule 1.1** Shall contain exactly one SPDX license identifier, which can
      express a single or multiple licenses (refer to SPDX_ for syntax details).

    - **Rule 1.2** The SPDX license identifier shall be added as a comment line.
      It shall be the first possible line in the file which can contain a
      comment. The comment style shall depend on the file type:

        - **Rule 1.2.1** C source: ``// SPDX-License-Identifier: <expression>``
        - **Rule 1.2.2** C header: ``/* SPDX-License-Identifier: <expression> */``
        - **Rule 1.2.3** Assembly: ``/* SPDX-License-Identifier: <expression> */``
        - **Rule 1.2.4** Python, shell: ``# SPDX-License-Identifier: <expression>``

    - **Rule 1.3** Shall contain at least one copyright line

    - **Rule 1.4** Shall not contain the mention 'All rights reserved'

    - **Rule 1.5** Shall not contain any license notice other than the SPDX license
      identifier

Note that files imported from external projects are not new files. The rules for
pre-existing files (below) apply.

Pre-existing or imported files
******************************

    - **Rule 2.1** SPDX license identifiers shall be added according to the
      license notice(s) in the file and the rules above (1.1 and 1.2*)

    - **Rule 2.2** It is recommended that license notices be removed once the
      corresponding identifier has been added. Note however that this may only
      be done by the copyright holder(s) of the file.

    - **Rule 2.3** Similar to 2.2, and subject to the same conditions, the text:
      "All rights reserved" shall be removed also.

.. _SPDX: https://spdx.org/licenses/